<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Flex实例布局</title>
</head>
<style>
  body {
    background-color: black;
  }
  .box{
    width: 100px;
    height: 100px;
    background-color: #fff;
    display: flex;
    /* center水平居中 / flex-end 右对齐 / space-between 两端对齐 / space-around 两端环绕对齐*/
    justify-content: space-between; 
    /* center垂直居中 flex-end 底部对齐  */
    /* align-items: flex-start; */
    /* flex-direction: column; */
  }
  .item {
    width: 20px;
    height: 20px;
    background-color: black;
    border-radius: 50%;
  }
  .item:nth-child(2) {
    /* align-self属性允许单个项目有与其他项目不一样的对齐方式 */
    align-self: center;
  }
  .item:nth-child(3) {
    /* align-self属性允许单个项目有与其他项目不一样的对齐方式 */
    align-self: flex-end;
  }
</style>
<body>
  <div class="box">
    <span class="item"></span>
    <span class="item"></span>
    <span class="item"></span>
  </div>
</body>

<script>

</script>
</html>